Greenhouse effect is primarily due to the presence of:

Which one of the following pairs of gases are the major cause of "greenhouse effect"?

$CO_{2}, CH_{4}, N_{2}O$ and $CFCs$ are called greenhouse gases because they can absorb:

Greenhouse effect refers to

The following pie chart shows the relative contribution of various greenhouse gases to total global warming. Which gases are represented by $P$, $Q$, and $R$?

The given diagram represents the greenhouse effect.
$I.$ Greenhouse gases absorb infrared radiation from the earth. The absorbed radiations are again emitted towards the earth's surface,heating it up.
$II.$ $CO_{2}, CH_{4}, CFCs$ and $N_{2}O$ are the gases responsible for the greenhouse effect.
$III.$ An increase in the level of greenhouse gases results in considerable heating of the earth,leading to global warming.
Which of the statements given above are correct?